Degasser



Jan. 13, 1959 H. H. DIETIIRICH DEGASSER Filed March 21, 1957 3 Sheets-Sheet 1 QINVENTOR Z awazd 1 0252%?! ATTORNEY Jan. 13, 1959 Q H. H. DlETRlCH 2,868,521

DEGASSER Filed March 21, 1957 3 Sheets-Sheet 2 1 IN VENTOR f" \\\\\i\i ATTORNEY Jan. 13, 1959 H. H. DIETRICH 2,868,521

, DEGASSER Filed March 21, 1957 5 Sheets-Sheet 5 INVENTOR ATTORNEY United States Patent DEGASSER Howard H. Dietrich, Rochester, N. Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 21, 1957, Serial No. 647,514 4 Claims. (Cl. 261-41) The present invention relates to a carburetor degassing or fuel cut-off mechanism for use with a carburetor and more particularly such a mechanism which may be adapted for use with carburetors not originally equipped therewith.

It has long been a problem in the carburetion field to prevent the fuel waste and atmospheric contamination occasioned by passing unburned hydrocarbons out of the exhaust system particularly under vehicle decelerating conditions. Carburetors as presently constituted are particularly susceptible to thus passing unburned fuel therethrough due to the high manifold vacuum which obtains during decelerating conditions. The high vacuum causes fuel to flow through the idle system in excess of that required for normal idling with theresult that the excess fuel is discharged into the atmosphere.

This contamination problem is particularly aggravating in large cities where thousands of automobiles are continuously discharging unburned hydrocarbons at the same time. Over a period of years various degassing devices have been developed to solve this problem. One of the difficulties arising with such degassing devices is the general expense and difliculty'in adapting'such to carburetors which did not include the same as original equipment.

The present invention is directed to providing an improved type degassing system which is readily adaptable to most automotive type carburetors now in use.

The present degassing system relates to a unique mechanism adapted to bleed the idle fuel passages to atmosphere in response to the high manifold vacuum which obtains during deceleration and thereby momentarily cutting olf the flow of idle fuel to prevent the discharge of unburned fuel.

It is also the purpose of this invention to provide means whereby a rapid recovery of the idle'fuel flow is achieved when degassing or fuel cut-01f is no longer required. In this respect the degassing unit itself provides a structure whereby the idle fuel cut-off takes place rapidly and further provides means which is active upon a decrease in manifold vacuum to provide a rapid recovery of fuel flow.

It is a further object of the invention to combine a unique non-flow reversing idle tube with the degassing unit which insures that idle fuel is readily available to resume normal engine operation when degassing is no longer necessary and in this way reduces the likelihood ofthe engine stalling for want of fuel.

.The details of the present invention as well as other objects and advantages will be apparent from a perusal of the description which follows.

In the drawings:

Figure 1 is a partially sectioned elevational view of a carburetor embodying the subject degasser;

Figure 2 is a bottom view of Figure 1;

Figure 3 is an enlarged sectional view of the degasser unit;

Figure 4 is an enlarged view along line 44 of Fig ure'3;

P a-tented Jan. 13, 1959 Figure 5 is an enlarged view along line 5-5 of Figure 3;

Figure 6 is an enlarged view along line 6-6 of Figure 3;

Figure 7 is an enlarged view along line 7-7 of Figure 4; and

Figure 8 is an enlarged view of the non-reversing idle tube.

A carburetor is shown generally at 8 and includes a fuel reservoir casing 10, a casing cover 12 and a throttle body 14. A throttle valve 16 is mounted in the throttle body and is adapted to control the quantity of combustible mixture flowing through the intake passage 18. A main fuel well 20 is formed in casing 10 and includes perforate main fuel nozzle 22 projecting therewithin. The main fuel nozzle is supported from the cover 12 and communicates through suitable passage means to the main fuel venturi, not shown. An idling fuel Well 24 is formed in the casing 10 proximate the main fuel well 20 and is in communication therewith. An idle fuel nozzle 26 is likewise supported from cover 12 and projects within the idle fuel well 24. An idle fuel passage 2.8 having appropriate atmospheric bleeds 30 is formed in cover 12 and communicates with idle nozzle 26. Passage 23 also communicates with additional idle fuel passages 32, 34 and 36 formed respectively in casing 10, degasser casing 38 and throttle body 14. The passages 28, 32, 34 and .36 with idle nozzle 26 constitute an idle fuel network which communicates with the induction passage 18 posteriorly of throttle 16 through an idle orifice a). An adjustable needle valve'42 is mounted on the throttle valve casing 14 and is adapted to regulate the opening of orifice 40 and thereby control the quantity of idle fuel flow.

Undernormal idling conditions with the throttle valve 16 closed, as shown, manifold vacuum will draw sufiicient idling fuel through orifice 4th to maintain the engine idling at a low speed. However, under decelerating conditions, e. g.the vehicle moving at relatively high speeds with the throttle closed, the high manifold vacuum draws fuel through the idling network in excess of that required to maintain the engine in an idling condition. This excess fuel is then passed through the exhaust system to the atmosphere in an unburned state since there is insufiicient air for complete combustion. To eliminate this condition a degasser unit indicated generally at St; is provided.

The degasser body is fabricated from casings 38, 52, f4 and 56 which are suitably connected together by studs 58 to provide an integral unit. Casing 38 includes a fiat plate-like portion 60 which is adapted to be placed between the float bowl casing 1t) and the throttle body 14. The plate portion 60 of casing 33 is suitably formed to provide an opening 62 corresponding to the induction passage opening and a passage 34 adapted to cooperate, as noted, in the idle fuel network. In addition any other passages or openings are provided in plate member 6! to preventinterference with the normal carburetor functions. Casing 38 is variously cored or bored to provide various passages necessary for operation of the degasser unit as will subsequently be considered in detail.

At this juncture it should be noted that the present degasser unit has been illustrated in combination with a two-barrel type carburetor. It is apparent, however, that the degasser unit is equally adaptable with carburetors having any number of induction passages. The only essential modification required to adapt the degasser to carburetors having more or less induction passages than shown being the necessity for providing more or less cored passages in the casing portion 60.

The throttle body 14 includes a recess 64 formed therein and which recessis adapted to communicate with a crossover passage 66 interconnecting the induction passages 18 posteriorly of the throtles 16. Recess 64 is, therefore, at

all times maintained under manifold depression. A passage 68 formed in the throttle body communicates recess 64 with a passage '70 formed in degasser casing portion 60. Passage 70 communicates with another passage 72 and in turn with passages or chambers 74, 76, 78 and 80 in the corresponding degasser casings 52, 54 and 56. In this way manifold vacuum is adapted to act on the degasser unit and bleed atmospheric air into the idling passages through passages 82, 84, 86, 88 and 99 also formed respectively in the casings 54, 52 and 38. The vacuum and atmospheric bleed passages are duplicated for each induction passage idle fuel network as indicated in Figure 2 and therefore it is only necessary to describe the operation of one set of such passages inasmuch as the remaining ones function in the same manner.

Degasser casings 54 and 56 have a diaphragm 92 peripherally clamped therebetween so as to define isolated chambers 94 and 96. The passageway 82 is formed through casing members 52 and 54 and communicates at one end with the atmosphere and is adapted to communicate at its other end with the chamber 96. When the degasser is inoperative a valve member 98 mounted on the diaphragm 92 blocks communication between atmospheric passage 82 and chamber 96. The casing 54 is counterbored at 100 to receive a valve seat 102 more clearly shown in Figure 6. The valve seat is recessed to provide pockets 104 communicating with the atmospheric idlc bleed passages 84, 86, 88 and 90. With the valve member 98 seated upon the valve seat, as shown in Fig ure 3, the respective pockets 104 are isolated from each other, as well as from atmospheric pocket 108, to prevent interconnection between the idle bleed networks of the respective induction passages.

Valve member 98 is connected to the diaphragm 92 through a socket 110 which is adapted to receive a ball 112 formed on a stud 114 suitably fastened to the reinforcing plates 116 and 118 on opposite sides of the diaphragm 92.

A stud member 120 is axially adjustably mounted in casing 56 and is adapted to be locked in any axial position by a nut 122. A spring seat 124 is fixed to stud 120 for supporting a spring member 126, the other end of which biases against the reinforcing plate 118 of the diaphragm 92 urging the latter and the valve member 92 to ward a position in which the valve member blocks communication of chambers 104 and 106 from the atmospheric chamber 108.

As already noted, manifold vacuum is adapted to be communicated through passage network 68-80 to chamber 94 in casing 56. Under normal running or idling conditions the manifold vacuum in chamber 94- is insufficient to overcome the force of spring 126 and therefore valve member 98 remains seated as shown. However, under decelerating conditions the manifold vacuum is increased to a value which will overcome the force of spring 126 to act on the diaphragm 92 and lift valve 98 from its seat 102. This, in turn, permits atmospheric air from passage 82 to be admitted into the idle fuel bleed passages 84-90 which interrupts the flow of fuel through the idling networks as described. At such time as the manifold vacuum is reduced to its normal level spring 126 will again reseat the valve 98 causing idle fuel flow to resume.

For the proper functioning of any degasser unit it is necessary that once the need for the fuel cut-off function has passed the idle fuel flow be restored as quickly as possible in order to prevent the engine from stalling for want of fuel or in the event such stalling has taken place to facilitate restarting of the engine as soon as possible. To this end a dual capacity valve indicated generally at 130 has been provided between the manifold vacuum passages 76 and 78 to change the rate of actuation of the diaphragm 92 and valve 98 to correspond more nearly with the requirements of the engine. Valve 130 includes discs 132 and 134 having concentric orifices 136 and 138 formed therethrough. Discs 132 and 134 are radially positioned within a counterbored portion 140 of passage 76 of casing member 52 by radially inward projecting portions 142 of the casing. A spring member 144 seated within a counterbored portion 146 within casing member 54 biases the discs axially against the face of counterbore 140 such that under normal conditions air flows through the orifices 136 and 138. At this point it should be observed that While a pair of discs 132 and 134 have been shown it would be equally possible to use a single disc with an orifice therein. Thus deceleration manifold vacuum will draw the air from casing chamber 94 through the orifices 136 and 138 causing the diaphragm 92 to open valve 98 at a given rate. However, as noted it is desired upon the completion of the degassing function to have the flow of idling fuel resumed as quickly as possible. To accommodate this desired function it is apparent that upon the drop in manifold vacuum the pressure on the carburetor side of the discs 132 and 134 will exceed that on the opposite side of the discs or in other words the vacuum in chamber 94 and passages 78-80 will exceed that in passages 74-76 etc. As a result of this pressure dilferential discs 132 and 134 will move to the right off its seat permitting the vacuum in chamber 94 to rapidly bleed around the discs as well as through the orifices and in this way permitting the spring 126 to rapidly return the valve 98 to its seat 102 to resume normal fuel flow.

As best seen in Figure 5, chamber 78 in casing 54 has radially inwardly projecting portions 150 which areadapted to engage and limit the axial opening movement of the discs 132 and 134.

In all normal idling systems, the idle fuel flow reverses whenever velocity and static vacuum at the main discharge nozzle exceeds a given value at the idle fuel orifice. Under normal operation, Whenever the throttle is opened, manifold vacuum drops substantially to zero and velocity vacuum at the main discharge nozzles causes reversal of air flow in the idle system. This bleeds all of the fuel out of the idle channels and replaces this fuel with air. Thus, when the idle channel is called upon to re-establish flow very quickly after the degasser unit has cut off fuel flow, the entire idle system must be filled up with fuel before it can start to feed. It is apparent that this causes an undesirable delay in the resumption of fuel flow. As seen in Figure 8, in the present system a non-flow reversing idle fuel nozzle 26 prevents the idle system from being bled out, by the main fuel system and, therefore, permits faster recovery of idle fuel after degassing has taken place.

The non-reversing nozzle 26 includes a first tubular member 160, the upper end of which is adapted to-be supported from cover casing 12 and the lower end of which is enlarged to provide an enlarged portion 162. A tubular section 164 having an annular flange 166 formed thereon is adapted to be disposed within the enlarged portion 162 of the sleeve 160. Section 164 is held within member by the abutment of the annular flange 166 against the gasketed sleeve shoulder 168 in conjunction with clamping the lower edge of sleeve 160 around the opposite face of the annular flange. A short tube section 170 is recessed into the sleeve 160 and includes a plurality of longitudinally extending recesses 172. A flow actuated valve member 174 is adapted to seat upon the upper end of tubular section 164. The diameter of valve member 174 is less than the internal diameter of recess 176 so that under normal operating conditions manifold vacuum will draw fuel upwardly through the tubular section 164 to lift valve 174 off of its seat and into abutment against the tubular section 170. Fuel will flow around the valve through the longitudinal recesses 172 and up through the tubular member 160 into the idle fuel network. In the event manifold vacuum drops below a value sufficient to draw fuel through the idling system and a reverse flow of such 'fuel is imminent, the flow reversal will cause the valve170 to seat upon the tubular section 164 and block the nozzle 26 against reverse flow. In this way the idling systern will be maintained fully charged with fuel ready for prompt delivery upon the demand of the system for idling fuel.

The non-reversing fuel nozzle as in combination with the quick acting vacuum neutralizing valve 13d provides a degassing system which is designed to reinstate the flow idling fuel as soon as the degassing function is no longer desired.

I claim:

1. A fuel system for an internal combustion engine comprising a carburetor having a float bowl on i '& throttle casing, an air induction passage formed throu h said casings, a throttle valve for controlling the quantity of combustible mixture flowing through said induction passage, an idle fuel Well formed in the float casing, a idling fuel nozzle disposed in said well and comn'iunieating with idle fuel passages formed in said float bowl and throttle casings, said idle fuel passages communicating with the induction passage posteriorly of the throttle valve, a degasser device supported upon said carburetor and including a plate-like casing member disposed between said fioat bowl and throttle casings, said degasser device including a passage means communicating with said idle fuel passages, valve means adapted to communicate said passage means to atmosphere, means normally biasing said valve to a position blocking communication of the passage means to atmosphere, servo means for actuating said valve, conduit means communicating said induction passage posteriorly of said throttle with said servo means whereby manifold vacuum is adapted to unseat said valve and admit atmospheric pressure to the idle fuel passages to interrupt the flow of fuel therethrough, and means in said conduit means for varying the rate of fluid flow therethrough.

2. A fuel system for an internal combustion engine comprising a carburetor having a float bowl casing, a throttle casing, an air induction passage formed through said casings, a throttle valve for controlling the quantity of combustible mixture flowing through said induction passage, an idle fuel well formed in the float casing, an idling fuel nozzle disposed in said well and communicating with idle fuel passages formed in said float bowl and throttle casings, said idle fuel passages being adapted to supply fuel to the induction passage posteriorly of the throttle valve when the throttle is closed, a valve in the idle nozzle for blocking the reverse flow of fuel through the nozzle, a degasser device supported upon said carburetor and including a plate-like casing member disposed between said float bowl and throttle casings, said degasser device including a passage means communicating with said idle fuel passages, valve means adapted to communicate said passage means to atmosphere, means normally biasing said valve to a position blocking communication of the passage means to atmosphere, servo means for actuating said valve, conduit means communicating said induction passage postericrly of said throttle with said servo means whereby manifold vacuum is adapted to unseat said valve and admit atmospheric pressure to the idle fuel passages to interrupt the flow of fuel therethrough, and orifice means in said vacuum conduit means for varying the rate of fluid flow therethrough.

3. A carbureting system including an induction passage, throttle means for controlling the flow of combustible mixture through said passage, an idle fuel network for bypassing fuel around said throttle valve when closed, and a mechanism for interrupting the flow of idling fuel when the manifold vacuum exceeds a given value, said mechanism comprising atmospheric bleed passage means adapted to communicate with the idle fuel system, manifold vacuum passage means communicating with the induction passage posteriorly of the throttle valve, valve means for blocking the flow of atmospheric air into said bleed passage means, a servo device in communication with said manifold passage means for opening said valve when the manifold vacuum reaches a given value, means for biasing said valve in a seated position, and flow controlling means cooperating with said manifold passage means to vary the rate of actuation of said servo device.

4. A carbureting system as set forth in claim 3 in which the flow controlling means comprises a perforate disc disposed in the manifold passage means and a spring element normally biasing against a seat causing manifold vacuum to evacuate said servo device through the perforation in said disc, vacuum in said servo device being adapted to unseat said disc upon a drop in manifold vacuum to rapidly reducethe Vacuum force in the servo device.

References Cited in the file of this patent UNITED STATES PATENTS 2,094,555 Von Hilvety Sept. 28, 1937 2,212,936 Hoof Aug. 27, 1940 2,346,711 Stupecky Apr. 18, 1944 2,448,131 Williams et a1 Aug. 31, 1948 2,763,285 Reeves Sept. 18, 1956 FOREIGN PATENTS 733,614 France July 12, 1932 

